Noun
A defect of the eye or of a lens, in consequence of which the rays derived from one point are not brought to a single focal point, thus causing imperfect images or indistinctness of vision.
Source: Webster's dictionaryHerschel considered astigmatism to be due to irregularity of the cornea and considered if vision could be improved by the application of some animal jelly contained in a capsule of glass against the cornea. Source: Internet
Astigmatism is an aberration that causes points to blur, degrading sharpness. Source: Internet
Astigmatism almost always occurs in both eyes and is usually quite symmetrical between the two. Source: Internet
Most astigmatism arised within the cornea although some forms occur in the lens. Source: Internet
For lenses that correct for astigmatism as well, three numbers are given: one for the spherical power, one for the cylindrical power, and one for the angle of orientation of the astigmatism. Source: Internet
In Latham and Matthews's Companion to the diary, Martin Howard Stein suggests that Pepys suffered from a combination of astigmatism and long sight. Source: Internet